1. Field of the Invention
The present invention relates to the electronic component of transformer and more particularly, to a receptacle for holding a transformer on a circuit board.
2. Description of the Related Art
A transformer generally comprises a bobbin, an iron core and windings. The bobbin comprises a plurality of primary-side contacts and secondary-side contacts. The lead wires of the primary winding and secondary winding are respectively electrically bonded to the primary-side contacts and secondary-side contacts. This is the basic architecture of a transformer.
When mounting a transformer on a circuit board, corresponding contacts are made at the circuit board, and then the primary-side contacts and secondary-side contacts of the transformer are respectively bonded to the contacts at the circuit board, finishing the installation. However, in some conditions where security requirements are critical, a relatively longer insulation distance between the contacts at the circuit board to which the secondary winding of the transformer is bonded and the contacts at the circuit board to which the primary winding of the transformer is bonded. In this case, the aforesaid conventional transformer installation method is not acceptable.
To meet the requirement for a relatively longer insulation distance, one conventional method is known by: directly extending the length of the lead wires 94′ of the secondary winding of the transformer 91′ and then bonding the lead wires 94′ to the circuit board. Thus, a distance L between the bonding ends of the lead wires 92′ of the primary winding of the transformer 91′ at the circuit board 99′ and the bonding ends of the lead wires 94′ of the secondary winding of the transformer 91′ at the circuit board 99′ that meets the security codes is obtained. According to this mounting method, the lead wires of the primary winding and the lead wires of the secondary winding are wrapped by an electrically insulative material, as shown in FIG. 17. Further, in another prior art design, the lead wires 92″ of the primary winding of the transformer 91″ are bare wires, and the lead wires 94″ of the secondary winding of the transformer 91″ are wrapped by an electrically insulative material. During installation, as shown in FIG. 18, the lead wires 94″ of the secondary winding of the transformer 91″ must be extended before bonding to the circuit board 99″ so that the insulation distance can meet the safety codes.
However, this installation method does not allow the presence of any device between the transformer and the secondary-side contacts, wasting much circuit board space. Under the market trend to create small size device or component, it is pity to waste circuit board in this manner.
Therefore, there is a demand for a measure to avoid wasting circuit board space while meeting safety codes.